Earplugs designed to be inserted into a person's ear canals to dampen sound and prevent the entry of foreign matter are known in the art. Historically, these earplugs were manufactured from fibrous materials such as cotton. In more recent times, earplugs have been produced from polymer based materials, which tend to be more durable than the fibrous materials formerly used. One conventional method for making polymer-based earplugs is by die cutting plugs from sheets of cellular material such as vinyl or polyurethane foam. Such die cut plugs are usually cylindrically shaped in order that the earplugs can readily conform to the shape of a human ear canal. As a result, the amount of material waste in die cut plug production tends to be great because the web between cut cylindrical earplugs cannot be used. Because the material used is often not recyclable, disposal of the waste material can represent a significant manufacturing expense. In addition, earplugs produced by this method customarily have cut cells along their cylindrical surfaces. As a result, they have a rough surface which can be uncomfortable to the wearer and harbor dirt. These earplugs can also be difficult to insert into a wearer's ear canals because they tend to lack longitudinal rigidity.
Another method for producing polymer-based earplugs is by molding them to the desired shape. For example, U.S. Pat. Nos. 4,774,938 and 3,872,559, both to Leight, disclose earplugs molded from polymer-based materials. Molded earplugs can be manufactured so that they are specially shaped and covered by a protective skin, enhancing their comfort and fit. However, the process of molding earplugs tends to be slower and more capital intensive than die cutting due to the large number of molds required. In addition, molded earplugs are often difficult to insert into a user's ears due to the fact that the polymer materials from which they are manufactured tend to lack longitudinal rigidity.
Attempts have been made to provide earplugs having sufficient longitudinal rigidity to allow them to be easily inserted into the ears and sufficient compressibility to allow snug yet comfortable wearer fit. For example, multi-component earplugs having a compressible element and a more rigid element are taught by U.S. Pat. No. 5,188,123 to Gardner, Jr. and U.S. Pat. No. 4,434,794 to Leight. Because the rigid and compressible elements of those earplugs must be individually manufactured and then joined together, their production processes tend to be slower and more costly than those for die cut earplugs. Thus a need exists for a readily manufacturable and inexpensive sound dampening earplug providing the requisite stiffness for easy ear insertion along with comfortable fit.